i am no midwife- and i am not sure in pregnancy- BUT i know that if you take too much it will give you very loose stools. it is a water souluble vitaman, so supposedly you cant take too much, but if you see those really loose stools, you know youve had enough!
It's too much Vitamin C when you start getting loose or watery stools. I take between 4-6 grams a day even when I am not sick. While you're pregnant, Vitamin C is excellent even when you are not sick because it supports your liver and kidney function. Hope that helps.
I usually take 2 grams a day, in addition to my prenatal and food/drinks that I have that contain vitamin C. If I start feeling sick I will start taking 2-3 grams 3 times a day. I haven't reached bowel tolerance yet and I hope I never do. :LOL
As a former dietitian, I can confidently tell you that your body cannot use more than 500 mg every 12 hrs. Any more than that will make very nutrient-rich urine. Vitamin C is water soluable and not stored in the body.